We experimentally investigate the effective working regions of a planar-integrated magneto-optical trap(MOT).By scanning a blocking point in the incident laser beam,we identify four effective working regions of the la...We experimentally investigate the effective working regions of a planar-integrated magneto-optical trap(MOT).By scanning a blocking point in the incident laser beam,we identify four effective working regions of the laser beam contributing to MOT:a central region corresponding to the downward incident beam and three regions associated with the upward diffracted beams.The latter three regions are the effective regions of the grating chip.It is demonstrated that only three3.5 mm radius grating regions can produce a MOT that is capable of trapping 105atoms with a temperature below 150μK,retaining over 60%of atoms compared to a complete grating chip.This finding suggests that more than 60%of the grating chip area can be saved for other on-chip components,such as metasurfaces and nanophotonic devices,without significantly compromising MOT performance,paving the way for more compact and versatile atom–photon interfaces.展开更多
A scanning and uniform array architecture with large spacing,low complexity and high scalability is presented for high integration massive array applications.It is constructed by offset phase center elements arranged ...A scanning and uniform array architecture with large spacing,low complexity and high scalability is presented for high integration massive array applications.It is constructed by offset phase center elements arranged in a uniform and regular way,but its spacing can be larger than that of traditional arrays.An ideal model of the offset phase center element is established and its far-field distribution is derived.To suppress grating lobes,the phase center of any element is designed to be movable without changing its physical position.Using genetic algorithm(GA),a new constraint condition limiting the number of phase center changes is proposed to solve the objective function of the minimum values of grating lobes(GLs)and side lobes(SLs).It is shown that the optimal results can be achieved by two changes of phase centers.A multimode circular patch is developed and designed,and characteristics of the offset phase center are analyzed and verified.A prototype array of 12×12 offset phase center elements is implemented based on multi-mode circular patches.Full wave simulation results of radiation patterns show that the level of grating lobes is suppressed at least 7dB with 1.12λ spacing,while the scanning angle is 20°.展开更多
Particle accelerators are indispensable tools in both science and industry.However,the size and cost of conventional RF accelerators limits the utility and scope of this technology.Recent research has shown that a die...Particle accelerators are indispensable tools in both science and industry.However,the size and cost of conventional RF accelerators limits the utility and scope of this technology.Recent research has shown that a dielectric laser accelerator(DLA)made of dielectric structures and driven at optical frequencies can generate particle beams with energies ranging from MeV to GeV at the tabletop level.To design DLA structures with a high acceleration gradient,we demonstrate topology optimization,which is a method used to optimize the material distribution in a specific area based on given load conditions,constraints,and performance indicators.To demonstrate the effectiveness of this approach,we propose two schemes and design several acceleration structures based on them.The optimization results demonstrate that the proposed method can be applied to structure optimization for on-chip integrated laser accelerators,producing manufacturable structures with significantly improved performance compared with previous size or shape optimization methods.These results provide new physical approaches to explore ultrafast dynamics in matter,with important implications for future laser particle accelerators based on photonic chips.展开更多
A modified multiwavelength actively mode-locked fiber ring laser is proposed and experimentally demonstrated. In this kind of laser, stable multiwavelengths lasing is achieved by integrating cascaded sampled fiber Bra...A modified multiwavelength actively mode-locked fiber ring laser is proposed and experimentally demonstrated. In this kind of laser, stable multiwavelengths lasing is achieved by integrating cascaded sampled fiber Bragg gratings(SFBGs) into the laser cavity. To implement actively mode-locking technique, a double-ring cavity configuration is used to assure that the cavity lengths for all wavelengths lasing are identical. Thus, simultaneous mode locking of all wavelengths has been successfully achieved by using the same mode-locking signal.展开更多
This paper introduces the design and applications of integrated As2S3 sidewall Bragg gratings on LiNbO3 substrate. The grating reflectance and bandwidth are analyzed with coupled-mode theory. Coupling coefficients are...This paper introduces the design and applications of integrated As2S3 sidewall Bragg gratings on LiNbO3 substrate. The grating reflectance and bandwidth are analyzed with coupled-mode theory. Coupling coefficients are computed by taking overlap integration. Numerical results for uniform gratings, phase-shifted gratings and grating cavities as well as electro-optic tunable gratings are presented. These integrated As2S3 sidewall gratings on LiNbO3 substrate provide an approach to the design of a wide range of integrated optical devices including switches, laser cavities, modulators, sensors and tunable filters.展开更多
Effectively managing floods in urban regions requires effectively designed and well-maintained runoff collection system. The absence of such a system and intense rainfall event will have the potential to disrupt the u...Effectively managing floods in urban regions requires effectively designed and well-maintained runoff collection system. The absence of such a system and intense rainfall event will have the potential to disrupt the urban life and cause significant economic loss to properties. Grated inlets, which are a key component in urban drainage network, are used to capture the runoff. In this work, a three dimensional CFD model was developed based on open-source CFD tool, OpenFOAM®, to model flow over a grated inlet. An incompressible, transient, multiphase flow, Volume of Fluid (VOF) simulation was performed to predict the water flow rate through the grate inlet. The predicted flow rates are compared with the HEC-22 monograph values. The close agreement between the results shows the potential of using CFD modeling approach to test the reliability of existing drainage inlets for different flow scenarios.展开更多
This study proposes a novel heterodyne grating interferometer designed to meet the multi-dimensional atomiclevel measurement demands of next-generation lithography systems and large-scale atomic-level manufacturing.By...This study proposes a novel heterodyne grating interferometer designed to meet the multi-dimensional atomiclevel measurement demands of next-generation lithography systems and large-scale atomic-level manufacturing.By utilizing a dual-frequency laser source,the interferometer enables simultaneous three-degree-of-freedom(3-DOF)displacement measurements.Key innovations include a compact,zero dead-zone optical path architecture,which enhances measurement robustness by minimizing sensitivity to laser source instabilities and atmospheric refractive index fluctuations.In addition,we present a systematic crosstalk error analysis,coupled with a corresponding compensation algorithm,effectively reducing crosstalk-induced errors to below 5%.Experimental evaluation of the 90×90×40 mm^(3) prototype demonstrates outstanding performance metrics:sub-nanometer resolutions(0.25 nm for X/Y-axes,0.3 nm for Z-axis),superior linearity coefficients(6.9×10^(−5),8.1×10^(−5),16.2×10^(−5) for X-,Y-,and Z-axes,respectively),high repeatability(0.8 nm@1000 nm for all axes),exceptional long-term stability(20 nm XY-plane drift,60 nm Z-axis drift over 1000 s),and practical measurement ranges exceeding 10 mm inplane and 2 mm axially.Comparative analysis with state-of-the-art sensors demonstrates significant advantages in measurement precision,system integration,and multi-axis capability.This advancement highlights excellent potential for applications in integrated circuit fabrication,atomic-scale manufacturing,and ultra-precision metrology for aerospace systems.展开更多
Leveraging the low linear and nonlinear absorption loss of silicon at mid-infrared(mid-IR)wavelengths,silicon photonic integrated circuits(PICs)have attracted significant attention for mid-IR applications including op...Leveraging the low linear and nonlinear absorption loss of silicon at mid-infrared(mid-IR)wavelengths,silicon photonic integrated circuits(PICs)have attracted significant attention for mid-IR applications including optical sensing,spectroscopy,and nonlinear optics.However,mid-IR silicon PICs typically show moderate performance compared to state-of-the-art silicon photonic devices operating in the telecommunication band.Here,we proposed and demonstrated suspended nanomembrane silicon(SNS)PICs with light-guiding within deep-subwavelength waveguide thickness for operation in the short-wavelength mid-IR region.We demonstrated key building components,namely,grating couplers,waveguide arrays,micro-resonators,etc.,which exhibit excellent performances in bandwidths,back reflections,quality factors,and fabrication tolerance.Moreover,the results show that the proposed SNS PICs have high compatibility with the multi-project wafer foundry services.Our study provides an unprecedented platform for mid-IR integrated photonics and applications.展开更多
Light detection and ranging(lidar)has attracted significant interest as a sensing technology for its ability to achieve highresolution imaging and wide-angle perception.However,conventional lidar systems,built with se...Light detection and ranging(lidar)has attracted significant interest as a sensing technology for its ability to achieve highresolution imaging and wide-angle perception.However,conventional lidar systems,built with separate components,are often bulky,expensive,complex,and prone to instability.In contrast,solid-state lidar,based on silicon photonics technology,offers a solution with its compact size,less expense,low energy consumption,and improved reliability.However,achieving precise beam steering remains a critical challenge for integrated lidar systems.Various methods have been demonstrated for beam steering,which is one of the simplest and most efficient approaches that utilize wavelength tuning with a grating coupler antenna.In this review,we introduce the fundamental principle of optical phased array for beam steering and provide an overview of the recent advancements in integrated solid-state lidars utilizing orthogonal polarizations and counterpropagation to enhance beam-steering range and angular resolution.展开更多
The silicon-based arrayed waveguide grating(AWG)is widely used due to its compact footprint and its compatibility with the mature CMOS process.However,except for AWGs with ridged waveguides of a few micrometers of cro...The silicon-based arrayed waveguide grating(AWG)is widely used due to its compact footprint and its compatibility with the mature CMOS process.However,except for AWGs with ridged waveguides of a few micrometers of cross section,any small process error will cause a large phase deviation in other AWGs,resulting in an increasing cross talk.In this paper,an ultralow cross talk AWG via a tunable microring resonator(MRR)filter is demonstrated on the SOI platform.The measured insertion loss and minimum adjacent cross talk of the designed AWG are approximately 3.2 and-45.1 d B,respectively.Compared with conventional AWG,its cross talk is greatly reduced.展开更多
We demonstrate an intracavity self-synchronized multi-color Q-switched fiber laser using a parallel-integrated fiber Bragg grating(PI-FBG), fabricated by a femtosecond laser with a point-by-point parallel inscription ...We demonstrate an intracavity self-synchronized multi-color Q-switched fiber laser using a parallel-integrated fiber Bragg grating(PI-FBG), fabricated by a femtosecond laser with a point-by-point parallel inscription method. The multi-color Q-switched pulses can be always self-synchronized when the group delay differences between neighboring spectra range from-3.4 to 3.4 ps.The starting and evolution dynamics indicate that the saturable absorption effect of the carbon nanotube plays a dual role: synchronously triggering the startup of the pulse at successive colors by active Q-switching and spontaneously compensating to some extent the temporal walk-off of the multi-color pulses through the cross saturable absorption modulation. This work unveils the intracavity self-synchronization mechanism of the multi-color Q-switched pulses and also demonstrates the potential of PI-FBGs for the customizable generation of the synchronized multi-color pulse in a single cavity.展开更多
To enhance the quality factor and sensitivity of refractive index sensors,a feedback waveguide slot grating micro-ring resonator was proposed.An air-hole grating structure was introduced based on the slot micro-ring,u...To enhance the quality factor and sensitivity of refractive index sensors,a feedback waveguide slot grating micro-ring resonator was proposed.An air-hole grating structure was introduced based on the slot micro-ring,utilizing the reflection of the grating to achieve the electromagnetic-like induced transparency effect at different wavelengths.The high slope characteristics of the EIT-like effect enabled a higher quality factor and sensitivity.The transmission principle of the structure was analyzed using the transmission matrix method,and the transmission spectrum and mode field distribution were simulated using the finite-difference time-domain(FDTD)method,and the device structure parameters were adjusted for optimization.Simulation results show that the proposed structure achieves an EIT-like effect with a quality factor of 59267.5.In the analysis of refractive index sensing characteristics,the structure exhibits a sensitivity of 408.57 nm/RIU and a detection limit of 6.23×10^(-5) RIU.Therefore,the proposed structure achieved both a high quality factor and refractive index sensitivity,demonstrating excellent sensing performance for applications in environmental monitoring,biomedical fields,and other areas with broad market potential.展开更多
Silicon photonics is an emerging competitive solution for next-generation scalable data communications in different application areas as high-speed data communication is constrained by electrical interconnects. Optica...Silicon photonics is an emerging competitive solution for next-generation scalable data communications in different application areas as high-speed data communication is constrained by electrical interconnects. Optical interconnects based on silicon photonics can be used in intra/inter-chip interconnects, board-to-board interconnects, short-reach communications in datacenters, supercomputers and long-haul optical transmissions. In this paper, we present an overview of recent progress in silicon optoelectronic devices and optoelectronic integrated circuits （OEICs） based on a complementary metal-oxide-semiconductor-compatible process, and focus on our research contributions. The silicon optoelectronic devices and OEICs show good characteristics, which are expected to benefit several application domains, including communication, sensing, computing and nonlinear systems.展开更多
We provide an overview of our recent work on developing subwavelength grating （SWG） waveguide devices as an enabling technology for integrated microwave photonics. First, we describe wavelength-selective SWG wavegui...We provide an overview of our recent work on developing subwavelength grating （SWG） waveguide devices as an enabling technology for integrated microwave photonics. First, we describe wavelength-selective SWG waveguide filters, including ring resonators, Bragg gratings, and contradirectional couplers. Second, we discuss the development of an index variable optical true time delay line that exploits spatial diversity in an equal-length waveguide array. These SWG waveguide components are fundamental building blocks for realizing more complex structures for advanced microwave photonic signal processing.展开更多
The fabrication and characterization of p-i-n photodiodes integrated with wide spectrum focusing reflectors using nonperiodic strip and concentric-circular subwavelength gratings are presented. The experimental result...The fabrication and characterization of p-i-n photodiodes integrated with wide spectrum focusing reflectors using nonperiodic strip and concentric-circular subwavelength gratings are presented. The experimental results show that the gratings can reflect and focus the incident light on the absorber of the photodiode, and thus can simultaneously achieve high speed and high efficiency. For the gratings’ integrated photodiodes, the responsivity is improved over a wide spectral range, and when the absorber was 600 nm and the mesa diameter was40 μm, a responsivity of 0.46 A/W at a wavelength of 1.55 μm and a 3 dB bandwidth of 21.6 GHz under a reverse bias of 3 V were simultaneously obtained.展开更多
A system of an add-drop microring resonator integrated with a sampled grating distributed feedback （SG-DFB） is investigated via modeling and simulation with the time-domain traveling wave （TDTW） method. The propos...A system of an add-drop microring resonator integrated with a sampled grating distributed feedback （SG-DFB） is investigated via modeling and simulation with the time-domain traveling wave （TDTW） method. The proposed microring resonator comprises a SiO2 waveguide integrated with an InGaAsP/InP SG-DFB, and the SiO2 waveguide consists of a silicon core having a refractive index of 3.48 and Kerr co- efficient of 4.5 × 10^-18 m2/W. The SG-DFB consists of a series of grating bursts that are constructed using a periodic apodization function with a burst spacing in the grating of 45 μm, a burst length of 5 μm, and I0 bursts across the total length of the SG-DBR. Transmission results of the through and drop port of the microring resonator show the significant capacity enhancement of the generated center wavelengths. The Q-factor of the microring resonator system, defined as the center wavelength （λ0） divided by 3 dB FWHM, without and with integration with the SG-DFB is calculated as 1.93 × 10^5 and 2.87 × 10^5, respectively. Analysis of the dispersion of the system reveals that increasing the wavelength results in a decrease of the dispersion. The higher capacity and efficiency are the advantages of integrating the microring resonator and the InGaAsP/InP SG-DFB.展开更多
With the support by the National Natural Science Foundation of China,a collaboration by the research groups led by Prof.Cheng Gang(程纲)from Henan University and Prof.Wang Zhonglin(王中林)from Beijing Institute of Nan...With the support by the National Natural Science Foundation of China,a collaboration by the research groups led by Prof.Cheng Gang(程纲)from Henan University and Prof.Wang Zhonglin(王中林)from Beijing Institute of Nanoenergy and Nanosystems,Chinese Academy of Sciences,invents'a sliding-mode triboelectric nanogenerator with chemical group grated structure by shadow mask reactive ion etching',which was published in ACS Nano(2017,11(9):8796-8803).展开更多
An ultra-small integrated photonic circuit has been proposed,which incorporates a high-quality-factor passive micro-ring resonator（MR） linked to a vertical grating coupler on a standard silicon-on-insulator（SOI） s...An ultra-small integrated photonic circuit has been proposed,which incorporates a high-quality-factor passive micro-ring resonator（MR） linked to a vertical grating coupler on a standard silicon-on-insulator（SOI） substrate.The experimental results demonstrate that the MR propagation loss is 0.532 dB/cm with a 10μm radius ring resonator,the intrinsic quality factor is as high as 202.000,the waveguide grating wavelength response curve is a 1 dB bandwidth of 40 nm at 1540 nm telecommunication wavelengths,and the measured fiber-to-fiber coupling loss is 10 dB.Furthermore,the resonator wavelength temperature dependence of the 450 nm wide micro-ring resonator is 54.1 pm/℃.Such vertical grating coupler and low loss MR-integrated components greatly promote a key element in biosensors and high-speed interconnect communication applications.展开更多
基金Project supported by the National Key R&D Program of China(Grant Nos.2021YFA1402004 and 2021YFF0603701)the National Natural Science Foundation of China(Grant Nos.12134014,U21A20433,U21A6006,and 92265108)+1 种基金supported by the Fundamental Research Funds for the Central UniversitiesUSTC Research Funds of the Double First-Class Initiative。
文摘We experimentally investigate the effective working regions of a planar-integrated magneto-optical trap(MOT).By scanning a blocking point in the incident laser beam,we identify four effective working regions of the laser beam contributing to MOT:a central region corresponding to the downward incident beam and three regions associated with the upward diffracted beams.The latter three regions are the effective regions of the grating chip.It is demonstrated that only three3.5 mm radius grating regions can produce a MOT that is capable of trapping 105atoms with a temperature below 150μK,retaining over 60%of atoms compared to a complete grating chip.This finding suggests that more than 60%of the grating chip area can be saved for other on-chip components,such as metasurfaces and nanophotonic devices,without significantly compromising MOT performance,paving the way for more compact and versatile atom–photon interfaces.
基金This work was supported by National Natural Science Foundation of China(No.U19B2028).
文摘A scanning and uniform array architecture with large spacing,low complexity and high scalability is presented for high integration massive array applications.It is constructed by offset phase center elements arranged in a uniform and regular way,but its spacing can be larger than that of traditional arrays.An ideal model of the offset phase center element is established and its far-field distribution is derived.To suppress grating lobes,the phase center of any element is designed to be movable without changing its physical position.Using genetic algorithm(GA),a new constraint condition limiting the number of phase center changes is proposed to solve the objective function of the minimum values of grating lobes(GLs)and side lobes(SLs).It is shown that the optimal results can be achieved by two changes of phase centers.A multimode circular patch is developed and designed,and characteristics of the offset phase center are analyzed and verified.A prototype array of 12×12 offset phase center elements is implemented based on multi-mode circular patches.Full wave simulation results of radiation patterns show that the level of grating lobes is suppressed at least 7dB with 1.12λ spacing,while the scanning angle is 20°.
基金the National Natural Science Foundation of China(Nos.12004353,11975214,11991071,11905202,12174350)Key Laboratory Foundation of The Sciences and Technology on Plasma Physics Laboratory(No.6142A04200103)Independent scientific research(No.JCKYS2021212011).
文摘Particle accelerators are indispensable tools in both science and industry.However,the size and cost of conventional RF accelerators limits the utility and scope of this technology.Recent research has shown that a dielectric laser accelerator(DLA)made of dielectric structures and driven at optical frequencies can generate particle beams with energies ranging from MeV to GeV at the tabletop level.To design DLA structures with a high acceleration gradient,we demonstrate topology optimization,which is a method used to optimize the material distribution in a specific area based on given load conditions,constraints,and performance indicators.To demonstrate the effectiveness of this approach,we propose two schemes and design several acceleration structures based on them.The optimization results demonstrate that the proposed method can be applied to structure optimization for on-chip integrated laser accelerators,producing manufacturable structures with significantly improved performance compared with previous size or shape optimization methods.These results provide new physical approaches to explore ultrafast dynamics in matter,with important implications for future laser particle accelerators based on photonic chips.
文摘A modified multiwavelength actively mode-locked fiber ring laser is proposed and experimentally demonstrated. In this kind of laser, stable multiwavelengths lasing is achieved by integrating cascaded sampled fiber Bragg gratings(SFBGs) into the laser cavity. To implement actively mode-locking technique, a double-ring cavity configuration is used to assure that the cavity lengths for all wavelengths lasing are identical. Thus, simultaneous mode locking of all wavelengths has been successfully achieved by using the same mode-locking signal.
文摘This paper introduces the design and applications of integrated As2S3 sidewall Bragg gratings on LiNbO3 substrate. The grating reflectance and bandwidth are analyzed with coupled-mode theory. Coupling coefficients are computed by taking overlap integration. Numerical results for uniform gratings, phase-shifted gratings and grating cavities as well as electro-optic tunable gratings are presented. These integrated As2S3 sidewall gratings on LiNbO3 substrate provide an approach to the design of a wide range of integrated optical devices including switches, laser cavities, modulators, sensors and tunable filters.
文摘Effectively managing floods in urban regions requires effectively designed and well-maintained runoff collection system. The absence of such a system and intense rainfall event will have the potential to disrupt the urban life and cause significant economic loss to properties. Grated inlets, which are a key component in urban drainage network, are used to capture the runoff. In this work, a three dimensional CFD model was developed based on open-source CFD tool, OpenFOAM®, to model flow over a grated inlet. An incompressible, transient, multiphase flow, Volume of Fluid (VOF) simulation was performed to predict the water flow rate through the grate inlet. The predicted flow rates are compared with the HEC-22 monograph values. The close agreement between the results shows the potential of using CFD modeling approach to test the reliability of existing drainage inlets for different flow scenarios.
基金supported by National Natural Science Foundation of China(NO.62275142)Shenzhen Stability Support Program Project(NO.WDZC 20231124201906001)Guangdong Basic and Applied Research Fund(NO.2021B1515120007).
文摘This study proposes a novel heterodyne grating interferometer designed to meet the multi-dimensional atomiclevel measurement demands of next-generation lithography systems and large-scale atomic-level manufacturing.By utilizing a dual-frequency laser source,the interferometer enables simultaneous three-degree-of-freedom(3-DOF)displacement measurements.Key innovations include a compact,zero dead-zone optical path architecture,which enhances measurement robustness by minimizing sensitivity to laser source instabilities and atmospheric refractive index fluctuations.In addition,we present a systematic crosstalk error analysis,coupled with a corresponding compensation algorithm,effectively reducing crosstalk-induced errors to below 5%.Experimental evaluation of the 90×90×40 mm^(3) prototype demonstrates outstanding performance metrics:sub-nanometer resolutions(0.25 nm for X/Y-axes,0.3 nm for Z-axis),superior linearity coefficients(6.9×10^(−5),8.1×10^(−5),16.2×10^(−5) for X-,Y-,and Z-axes,respectively),high repeatability(0.8 nm@1000 nm for all axes),exceptional long-term stability(20 nm XY-plane drift,60 nm Z-axis drift over 1000 s),and practical measurement ranges exceeding 10 mm inplane and 2 mm axially.Comparative analysis with state-of-the-art sensors demonstrates significant advantages in measurement precision,system integration,and multi-axis capability.This advancement highlights excellent potential for applications in integrated circuit fabrication,atomic-scale manufacturing,and ultra-precision metrology for aerospace systems.
基金partly supported by the National Natural Science Foundation of China(NSFC)(62175179,62161160335)Natural Science Foundation of Tianjin Municipality,China(23JCJQJC00250)+1 种基金Natural Science Foundation of Guangdong Province,China(2022B1515130002,2023A1515011189)Japan Society for the Promotion of Science(JSPS)(JP18K13798).
文摘Leveraging the low linear and nonlinear absorption loss of silicon at mid-infrared(mid-IR)wavelengths,silicon photonic integrated circuits(PICs)have attracted significant attention for mid-IR applications including optical sensing,spectroscopy,and nonlinear optics.However,mid-IR silicon PICs typically show moderate performance compared to state-of-the-art silicon photonic devices operating in the telecommunication band.Here,we proposed and demonstrated suspended nanomembrane silicon(SNS)PICs with light-guiding within deep-subwavelength waveguide thickness for operation in the short-wavelength mid-IR region.We demonstrated key building components,namely,grating couplers,waveguide arrays,micro-resonators,etc.,which exhibit excellent performances in bandwidths,back reflections,quality factors,and fabrication tolerance.Moreover,the results show that the proposed SNS PICs have high compatibility with the multi-project wafer foundry services.Our study provides an unprecedented platform for mid-IR integrated photonics and applications.
基金supported by the Shaanxi Province Innovation Talent Promotion Program Science and Technology Innovation Team(No.2023-CX-TD-03)the Natural Science Foundation of Shaanxi Province(No.2023-JC-YB-587)+1 种基金the National Key Research and Development Program of China(No.2019YFB1803700)the Key Technologies Research and Development Program of Tianjin(No.20YFZCGX00440).
文摘Light detection and ranging(lidar)has attracted significant interest as a sensing technology for its ability to achieve highresolution imaging and wide-angle perception.However,conventional lidar systems,built with separate components,are often bulky,expensive,complex,and prone to instability.In contrast,solid-state lidar,based on silicon photonics technology,offers a solution with its compact size,less expense,low energy consumption,and improved reliability.However,achieving precise beam steering remains a critical challenge for integrated lidar systems.Various methods have been demonstrated for beam steering,which is one of the simplest and most efficient approaches that utilize wavelength tuning with a grating coupler antenna.In this review,we introduce the fundamental principle of optical phased array for beam steering and provide an overview of the recent advancements in integrated solid-state lidars utilizing orthogonal polarizations and counterpropagation to enhance beam-steering range and angular resolution.
基金supported by the National Key Research and Development Program of China(No.2018YFB2200500)the Yunnan Provincial Foundation Program(No.202201AT070202)the National Natural Science Foundation of China(No.62065010)。
文摘The silicon-based arrayed waveguide grating(AWG)is widely used due to its compact footprint and its compatibility with the mature CMOS process.However,except for AWGs with ridged waveguides of a few micrometers of cross section,any small process error will cause a large phase deviation in other AWGs,resulting in an increasing cross talk.In this paper,an ultralow cross talk AWG via a tunable microring resonator(MRR)filter is demonstrated on the SOI platform.The measured insertion loss and minimum adjacent cross talk of the designed AWG are approximately 3.2 and-45.1 d B,respectively.Compared with conventional AWG,its cross talk is greatly reduced.
基金supported by the National Natural Science Foundation of China (No.12274344)the Natural Science Basic Research Program of Shaanxi (No.2023-JC-YB-563)the Guangdong Basic and Applied Basic Research Foundation (No.2023A1515011517)。
文摘We demonstrate an intracavity self-synchronized multi-color Q-switched fiber laser using a parallel-integrated fiber Bragg grating(PI-FBG), fabricated by a femtosecond laser with a point-by-point parallel inscription method. The multi-color Q-switched pulses can be always self-synchronized when the group delay differences between neighboring spectra range from-3.4 to 3.4 ps.The starting and evolution dynamics indicate that the saturable absorption effect of the carbon nanotube plays a dual role: synchronously triggering the startup of the pulse at successive colors by active Q-switching and spontaneously compensating to some extent the temporal walk-off of the multi-color pulses through the cross saturable absorption modulation. This work unveils the intracavity self-synchronization mechanism of the multi-color Q-switched pulses and also demonstrates the potential of PI-FBGs for the customizable generation of the synchronized multi-color pulse in a single cavity.
基金supported by Natural Science Foundation of Gansu Province(NO.21JR7RA289)。
文摘To enhance the quality factor and sensitivity of refractive index sensors,a feedback waveguide slot grating micro-ring resonator was proposed.An air-hole grating structure was introduced based on the slot micro-ring,utilizing the reflection of the grating to achieve the electromagnetic-like induced transparency effect at different wavelengths.The high slope characteristics of the EIT-like effect enabled a higher quality factor and sensitivity.The transmission principle of the structure was analyzed using the transmission matrix method,and the transmission spectrum and mode field distribution were simulated using the finite-difference time-domain(FDTD)method,and the device structure parameters were adjusted for optimization.Simulation results show that the proposed structure achieves an EIT-like effect with a quality factor of 59267.5.In the analysis of refractive index sensing characteristics,the structure exhibits a sensitivity of 408.57 nm/RIU and a detection limit of 6.23×10^(-5) RIU.Therefore,the proposed structure achieved both a high quality factor and refractive index sensitivity,demonstrating excellent sensing performance for applications in environmental monitoring,biomedical fields,and other areas with broad market potential.
基金supported by the National Basic Research Program of China(No.2011CBA00608)the National Natural Science Foundation of China(Nos.61178051,61321063,61335010,61178048,61275169)the National High Technology Research and Development Program of China(Nos.2013AA013602,2013AA031903,2013AA032204)
文摘Silicon photonics is an emerging competitive solution for next-generation scalable data communications in different application areas as high-speed data communication is constrained by electrical interconnects. Optical interconnects based on silicon photonics can be used in intra/inter-chip interconnects, board-to-board interconnects, short-reach communications in datacenters, supercomputers and long-haul optical transmissions. In this paper, we present an overview of recent progress in silicon optoelectronic devices and optoelectronic integrated circuits （OEICs） based on a complementary metal-oxide-semiconductor-compatible process, and focus on our research contributions. The silicon optoelectronic devices and OEICs show good characteristics, which are expected to benefit several application domains, including communication, sensing, computing and nonlinear systems.
基金supported in part by the Natural Sciences and Engineering Research Council of Canadathe Fonds de Recherche du Québec-Nature et Technologies,and the Royal Society
文摘We provide an overview of our recent work on developing subwavelength grating （SWG） waveguide devices as an enabling technology for integrated microwave photonics. First, we describe wavelength-selective SWG waveguide filters, including ring resonators, Bragg gratings, and contradirectional couplers. Second, we discuss the development of an index variable optical true time delay line that exploits spatial diversity in an equal-length waveguide array. These SWG waveguide components are fundamental building blocks for realizing more complex structures for advanced microwave photonic signal processing.
基金funded by the National Natural Science Foundation of China(NSFC)(Nos.61574019,61674020,and 61274044)the 111 Project(No.B07005)+2 种基金the Beijing Municipality Natural Science Foundation(No.4132069)the Program for Changjiang ScholarsInnovative Research Team in University through the Ministry of Education of China(No.IRT0609)
文摘The fabrication and characterization of p-i-n photodiodes integrated with wide spectrum focusing reflectors using nonperiodic strip and concentric-circular subwavelength gratings are presented. The experimental results show that the gratings can reflect and focus the incident light on the absorber of the photodiode, and thus can simultaneously achieve high speed and high efficiency. For the gratings’ integrated photodiodes, the responsivity is improved over a wide spectral range, and when the absorber was 600 nm and the mesa diameter was40 μm, a responsivity of 0.46 A/W at a wavelength of 1.55 μm and a 3 dB bandwidth of 21.6 GHz under a reverse bias of 3 V were simultaneously obtained.
基金Grant number LRGS(2015)NGOD/UM/KPT,RU007/2015 and RUG OF UTM,09H77 and 10J97 from the university of Malaya (UM) and Universiti Teknologi Malaysia (UTM)
文摘A system of an add-drop microring resonator integrated with a sampled grating distributed feedback （SG-DFB） is investigated via modeling and simulation with the time-domain traveling wave （TDTW） method. The proposed microring resonator comprises a SiO2 waveguide integrated with an InGaAsP/InP SG-DFB, and the SiO2 waveguide consists of a silicon core having a refractive index of 3.48 and Kerr co- efficient of 4.5 × 10^-18 m2/W. The SG-DFB consists of a series of grating bursts that are constructed using a periodic apodization function with a burst spacing in the grating of 45 μm, a burst length of 5 μm, and I0 bursts across the total length of the SG-DBR. Transmission results of the through and drop port of the microring resonator show the significant capacity enhancement of the generated center wavelengths. The Q-factor of the microring resonator system, defined as the center wavelength （λ0） divided by 3 dB FWHM, without and with integration with the SG-DFB is calculated as 1.93 × 10^5 and 2.87 × 10^5, respectively. Analysis of the dispersion of the system reveals that increasing the wavelength results in a decrease of the dispersion. The higher capacity and efficiency are the advantages of integrating the microring resonator and the InGaAsP/InP SG-DFB.
文摘With the support by the National Natural Science Foundation of China,a collaboration by the research groups led by Prof.Cheng Gang(程纲)from Henan University and Prof.Wang Zhonglin(王中林)from Beijing Institute of Nanoenergy and Nanosystems,Chinese Academy of Sciences,invents'a sliding-mode triboelectric nanogenerator with chemical group grated structure by shadow mask reactive ion etching',which was published in ACS Nano(2017,11(9):8796-8803).
基金supported by the National Basic Research Program of China(No.2009CB326206)the National Natural Science Foundation of China(Nos.61076111,50975266)+2 种基金the Key Laboratory Fund of China(No.9140C1204040909)the Graduate Innovation Project of China (No.20103083)the Fund for Top Young Academic Leaders of Higher Learning Institutions of Shanxi(TYAL),China
文摘An ultra-small integrated photonic circuit has been proposed,which incorporates a high-quality-factor passive micro-ring resonator（MR） linked to a vertical grating coupler on a standard silicon-on-insulator（SOI） substrate.The experimental results demonstrate that the MR propagation loss is 0.532 dB/cm with a 10μm radius ring resonator,the intrinsic quality factor is as high as 202.000,the waveguide grating wavelength response curve is a 1 dB bandwidth of 40 nm at 1540 nm telecommunication wavelengths,and the measured fiber-to-fiber coupling loss is 10 dB.Furthermore,the resonator wavelength temperature dependence of the 450 nm wide micro-ring resonator is 54.1 pm/℃.Such vertical grating coupler and low loss MR-integrated components greatly promote a key element in biosensors and high-speed interconnect communication applications.
